Thiol Compounds Inhibit the Formation of Amyloid Fibrils by β2-Microglobulin at Neutral pH

Yamamoto, Kaori; Yagi, Hisashi; Ozawa, Daisaku; Sasahara, Kazutoshi; Naiki, Hironobu; Goto, Yuji

doi:10.1016/j.jmb.2007.12.002

Cited by 39 publications

(30 citation statements)

References 46 publications

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“…First, ␤2-m and K3 fibrils were grown in test tubes at pH 7.0 and pH 6.0, respectively, based on the conditions established in our previous studies (23,28). TIRFM images indicated the presence of short fibrils in each sample (data not shown), confirming that amyloid-specific fluorescence from ThT enables to the visualization of both ␤2-m and K3 fibrils.…”

Section: Effects Of Various Surfaces On ␤2-m and K3 Fibrils-tomentioning

confidence: 57%

Destruction of Amyloid Fibrils of a β2-Microglobulin Fragment by Laser Beam Irradiation

Ozawa

Yagi

Ban

et al. 2009

Journal of Biological Chemistry

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To understand the mechanism by which amyloid fibrils form, we have been making real-time observations of the growth of individual fibrils, using total internal fluorescence microscopy combined with an amyloid-specific fluorescence dye, thioflavin T (ThT). At neutral pH, irradiation at 442 nm with a laser beam to excite ThT inhibited the fibril growth of ␤ 2 -microglobulin (␤2-m), a major component of amyloid fibrils deposited in patients with dialysis-related amyloidosis. Examination with a 22-residue K3 fragment of ␤2-m showed that the inhibition of fibril growth and moreover the destruction of preformed fibrils were coupled with the excitation of ThT. Several pieces of evidence suggest that the excited ThT transfers energy to ground state molecular oxygen, producing active oxygen, which causes various types of chemical modifications. The results imply a novel strategy for preventing the deposition of amyloid fibrils and for destroying preformed amyloid deposits.Amyloid fibrils are associated with the pathogenesis of more than 20 serious diseases, including Alzheimer, Parkinson, and Huntington diseases, and dialysis-related amyloidosis (1, 2). Moreover, various proteins and peptides that are not related to diseases can also form amyloid-like fibrils, implying that the formation of fibrils is a generic property of proteins and peptides (1). In basic structure, amyloid fibrils are long and often twisted, a few nanometers in diameter, and predominantly composed of cross ␤-sheets (1, 3). Amyloid fibrils are formed spontaneously with a lag phase or seed-dependently without a lag time, indicating that they are formed by nucleation and extension. Further understanding of the structure, mechanism of formation, and roles in amyloidosis is one of the most important issues of protein science today.To study amyloid fibrils, we developed a unique technique for their direct observation in which total internal reflection fluorescence microscopy (TIRFM) 2 is combined with amyloidspecific thioflavin T (ThT) fluorescence (4 -8). This technique provides important information about the morphology, growth rate, and extension direction of fibrils in real time at the single fibril level. We have applied the technique to the fibrils of ␤ 2 -microglobulin (␤2-m) responsible for dialysis-related amyloidosis and amyloid ␤ associated with Alzheimer disease (4 -8).␤2-m is a major component of amyloid fibrils deposited in dialysis-related amyloidosis, a common and serious complication in patients receiving hemodialysis for more than 10 years (9 -11). ␤2-m, a typical immunoglobulin domain made of 99 amino acid residues and seven ␤-stands, is present as the nonpolymorphic light chain of the class I major histocompatibility complex (12). Renal failure disrupts the clearance of ␤2-m from the serum and, moreover, ␤2-m does not pass through the dialysis membrane, resulting in an increase in the concentration of ␤2-m in blood by up to 50-fold. Although an increase in the concentration of ␤2-m is the most important risk factor for fibrillation, how...

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Section: Effects Of Various Surfaces On ␤2-m and K3 Fibrils-tomentioning

confidence: 57%

Destruction of Amyloid Fibrils of a β2-Microglobulin Fragment by Laser Beam Irradiation

Ozawa

Yagi

Ban

et al. 2009

Journal of Biological Chemistry

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“…A key difference between these and the current studies is their use of agitation rather than quiescent solution conditions. It is well established that agitation promotes the aggregation of many proteins, often as amyloid (8,38,39). This is not well understood but likely involves interface effects and perhaps also accelerated oxidation of free thiols.…”

Section: In the Absence Of Als-associated Mutations Reduced Apo Sod1mentioning

confidence: 99%

Decreased stability and increased formation of soluble aggregates by immature superoxide dismutase do not account for disease severity in ALS

Vassall¹,

Stubbs²,

Primmer³

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

145

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Protein aggregation is a hallmark of many diseases, including amyotrophic lateral sclerosis (ALS), where aggregation of Cu/Zn superoxide dismutase (SOD1) is implicated in causing neurodegeneration. Recent studies have suggested that destabilization and aggregation of the most immature form of SOD1, the disulfide-reduced, unmetallated (apo) protein is particularly important in causing ALS. We report herein in depth analyses of the effects of chemically and structurally diverse ALS-associated mutations on the stability and aggregation of reduced apo SOD1. In contrast with previous studies, we find that various reduced apo SOD1 mutants undergo highly reversible thermal denaturation with little aggregation, enabling quantitative thermodynamic stability analyses. In the absence of ALS-associated mutations, reduced apo SOD1 is marginally stable but predominantly folded. Mutations generally result in slight decreases to substantial increases in the fraction of unfolded protein. Calorimetry, ultracentrifugation, and light scattering show that all mutations enhance aggregation propensity, with the effects varying widely, from subtle increases in most cases, to pronounced formation of 40–100 nm soluble aggregates by A4V, a mutation that is associated with particularly short disease duration. Interestingly, although there is a correlation between observed aggregation and stability, there is minimal to no correlation between observed aggregation, predicted aggregation propensity, and disease characteristics. These findings suggest that reduced apo SOD1 does not play a dominant role in modulating disease. Rather, additional and/or multiple forms of SOD1 and additional biophysical and biological factors are needed to account for the toxicity of mutant SOD1 in ALS.

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“…Other investigations have provided evidence of the correlation between disulfide bond and amyloid fibrillation of proteins including Familial British Dementia associated ABri, 63 transthyretin, 64 β 2 -microglobulin, 31 and short synthetic peptides. 65 As in the cases of proteins relevant in food industry, Thorn and coworkers previously illustrated that the fibril formation of bovine milk κ-casein under near physiological conditions (37°C and pH 7.4) was promoted upon reduction of its intermolecular disulfide linkages; 46 however, an initial exposure of α S2 -casein to the reducing agent DTT brought about the suppression of amyloid fibrillation.…”

Section: Discussionmentioning

confidence: 99%

“…[27][28][29] Previous studies have demonstrated that the thiol-containing reducing agents interfere with the fibrillation/aggregation of hen egg-white lysozyme, β-2-microglobulin, and α-synuclein. [30][31][32] Herein, we describe a series of experiments in which we examined how glutathione affects the fibrillation of α-lactalbumin, a major protein in whey protein isolate (WPI), at pH 2.2 and 55°C.…”

Section: Introductionmentioning

confidence: 99%

Fibril Formation of Bovine α-Lactalbumin Is Inhibited by Glutathione

et al. 2011

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The current research is aimed at exploring the inhibitory effect of glutathione on fibril formation of an important four disulfide bond-containing whey protein, α-lactalbumin. Through numerous spectroscopic techniques and transmission electron microscopy, we found that the inhibition of amyloid formation of α-lactalbumin was dependent on the glutathione concentration and fibrillation was significantly attenuated in the presence of 5 mM glutathione. Moreover, the data from the measurements using 4,4′-dithiodipyridine reagent revealed that the treatment of α-lactalbumin with glutathione led to the exposure of sulfhydryl groups. Also, the observed inhibition of α-lactalbumin by glutathione was correlated with the reduction of disulfide bridges of protein. The results presented here suggest that the addition of food compatible reducing agent/dietary supplement such as glutathione would be useful for preventing the formation of milk protein fibrillar aggregates. The presence of these resulting aggregates can then, in turn, be used to modulate the key properties of food products such as protein beverage and yogurt.

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Thiol Compounds Inhibit the Formation of Amyloid Fibrils by β2-Microglobulin at Neutral pH

Cited by 39 publications

References 46 publications

Destruction of Amyloid Fibrils of a β2-Microglobulin Fragment by Laser Beam Irradiation

Destruction of Amyloid Fibrils of a β2-Microglobulin Fragment by Laser Beam Irradiation

Decreased stability and increased formation of soluble aggregates by immature superoxide dismutase do not account for disease severity in ALS

Fibril Formation of Bovine α-Lactalbumin Is Inhibited by Glutathione

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